Quick Buying Guide

Diamond prices vary greatly as they depend on the combination of unique characteristics (4Cs - Cut, Color, Clarity, and Carat). For best value, it's important to choose the combination that will reduce the price without having a negative impact on appearance.

Each shape has its own recommended balance of qualities that will give you the most bang for your buck. With Rounds, for example, you can go relatively low in terms of color and clarity without compromising on beauty. However, you should never skimp on the cut. Below is a quick buying guide to give you an idea, but for more detailed explanation, please see the complete buying guides for the respective diamonds (links below).

Depth percentage for 0.18 carat
Round
(3.5×3.5×2.11mm)

Depth percentage of Round cut is the ratio of the total depth (measured from table to culet)
to its average diameter. The total depth percentage of this diamond
is 60.3%, which is OK.
(Recommended depth percentage for Rounds is between 58% and
62.5%)

Depth percentage for rounds is calculated with the following formula:

Depth % = (total depth ÷ average diameter) × 100

0.18 carat
Round
(3.5×3.5×2.11mm) depth %:

Total depth: 2.11 mm
Average diameter = (3.5 + 3.5) ÷ 2 = 3.5 mm

Depth % = (2.11 ÷ 3.5 ) × 100 = 60.3%

Depth percentage for 0.5 carat
Round
(5.16×5.16×3.11mm)

Depth percentage of Round cut is the ratio of the total depth (measured from table to culet)
to its average diameter. The total depth percentage of this diamond
is 60.3%, which is OK.
(Recommended depth percentage for Rounds is between 58% and
62.5%)

Depth percentage for rounds is calculated with the following formula:

Depth % = (total depth ÷ average diameter) × 100

0.5 carat
Round
(5.16×5.16×3.11mm) depth %:

Total depth: 3.11 mm
Average diameter = (5.16 + 5.16) ÷ 2 = 5.16 mm

Depth % = (3.11 ÷ 5.16 ) × 100 = 60.3%

About Depth Percentage

Depth percentage is one of the most important measurements as it plays a critical role in diamond's
appearance. If a diamond is cut too deep or too shallow, light leaks out, making
the stone less brilliant and fiery. Deep cuts also add hidden weight.

Diamonds that fall out of recommended depth range are generally less desirable
and usually best to be avoided.

Face-up size evaluation for 0.18 carat Round
(3.5×3.5×2.11mm)

The face-up size of this 0.18 carat Round
(3.5×3.5×2.11mm) is out of normal range for
0.18ct diamonds of this shape. A well cut 0.18ct Round
should have an average diameter between 3.58 and 3.73 mm. Compared to 0.18
carat Round reference diamond,
this diamond appears too small when viewed from the top, which makes it a chubby.

A chubby is a diamond with hidden extra weight that looks smaller than it should when
viewed from the top. Hidden weight is typically a result of a poor cut usually linked to oversized
girdle, deeper pavilion, and/or steeper crown.

In order to maximize profits, diamond cutters tend to retain as much weight from the rough
as possible. This practice, however, can have detrimental effects on the stone's face-up
size and its optical qualities. Poorly proportioned stones look duller and sparkle less than
well cut stones. Chubby stones also look smaller.

The bottom line:
One should never sacrifice beauty for weight.
You probably don't want to pay for extra weight that doesn't add anything to the beauty.
You want a stone that looks its weight. This one doesn't - sizewise, it looks like a well cut 0.16ct diamond.

0.18 carat Round reference diamond

0.18ct Round reference diamond is calculated from the following ideal proportions:

Proportions:

Table:

57%

Crown angle:

34°

Pavilion angle:

40.7°

Girdle:

2.8%

Star length:

50%

Lower half-length:

80%

Culet:

None

Calculated values:

Depth:

60.3%

Crown height:

14.5%

Pavilion height:

43%

For 0.18 carat weight:

Diameter:

3.67 mm

Face-up area:

10.58 mm²

Note: Round diamonds with face-up area of within 5% lower
and 3% higher than reference Round diamond area
are considered to be of adequate face-up size.

Face-up size evaluation for 0.5 carat Round
(5.16×5.16×3.11mm)

The face-up size of this 0.5 carat Round
(5.16×5.16×3.11mm) is within the normal range for
0.5ct diamonds of this shape.
Compared to 0.5ct
Round reference diamond (see below), this diamond is of adequate
size when viewed from the top. In short, all is OK, this diamond looks its weight.

The importance of face-up size

Diamonds are sold by weight (carats), but it's important to understand that
weight doesn't equally translate into physical size, especially spread. Two
diamonds of the same carat weight can vary greatly in spread, meaning that one
diamond can appear larger than the other, even though they weight exactly the same.

Proper face-up size should play an important role when buying a diamond.
When a diamond is set in a ring, your eyes will only see the face-up area,
so you should make sure it's of adequate size. Adequate size also indicates a good cut, meaning better light performance. Would you want a poorly cut 0.5 carat diamond that is less sparkly and has the same face-up size as an ideal cut 0.4 carat? Probably not.

The bottom line:
A diamond must look its weight. This one does. Thumbs up.

0.5 carat Round reference diamond

0.5ct Round reference diamond is calculated from the following ideal proportions:

Proportions:

Table:

57%

Crown angle:

34°

Pavilion angle:

40.7°

Girdle:

2.8%

Star length:

50%

Lower half-length:

80%

Culet:

None

Calculated values:

Depth:

60.3%

Crown height:

14.5%

Pavilion height:

43%

For 0.5 carat weight:

Diameter:

5.16 mm

Face-up area:

20.91 mm²

Note: Round diamonds with face-up area of within 5% lower
and 3% higher than reference Round diamond area
are considered to be of adequate face-up size.

Face-up Area per Carat

Face-up area per carat is calculated by dividing face-up area of the diamond with
its carat weight. It tells you how many square millimeters of the top surface area
a diamond is showing or would show for 1 carat weight. This can be useful when comparing stones
of similar weights as it tells you how much spread per carat you will get.

Note: Face-up size does not linearly grow with carat weight,
which means the heavier the stone, the smaller its face-up area per carat (e.g., 1ct stone will have
higher face-up area per carat than 2ct stone).

Face-up area per carat
for 0.18ct Round (3.5×3.5×2.11mm):

Top surface area = 9.62 mm²Weight = 0.18ct

Face-up area per carat = 9.62 ÷ 0.18 =
53.44mm²/ct

Face-up area per carat
for 0.5ct Round (5.16×5.16×3.11mm):

Top surface area = 20.91 mm²Weight = 0.5ct

Face-up area per carat = 20.91 ÷ 0.5 =
41.82mm²/ct

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